Hydroformylation, for production of linear (normal) and branched (iso) aldehydes, a carbon number of each of which is increased by one, by reacting various olefins with carbon monoxide (CO) and hydrogen (H2), which are generally referred to as synthesis gases, in the presence of a homogeneous organometallic catalyst and a ligand, was first discovered by Otto Roelen in Germany in 1938.
Hydroformylation, which is also known as oxo synthesis, is very important in industrial homogeneous catalytic reaction. Throughout the world, various aldehydes including alcohol derivatives are produced and consumed through the oxo process.
Various aldehydes, which are synthesized by oxo reaction, may be modified into various acids and alcohols with a long alkyl group by performing oxidization and hydrogenation after performing condensation reaction with aldol or the like. In particular, a hydrogenated alcohol, which is derived from an aldehyde synthesized by such oxo synthesis, is called an oxo alcohol. Such an oxo alcohol is widely utilized industrially as a raw material of solvents, additives, various plasticizers, synthetic lubricating oils, and the like.
Conventionally, the value of linear (normal) aldehyde derivatives among aldehydes generated by oxo synthesis was high, whereby most research on catalysts has focused on increasing the proportion of linear aldehyde derivatives. However, in recent years, isobutyric acid, neopentyl glycol (NPG), 2,2,4-trimethyl-1,3-pentanediol, isovaleric acid and the like, which use a branched aldehyde derivative (iso-aldehyde) as a raw material, were developed, and thus, demand for iso-aldehydes has increased. Accordingly, research has been carried out to increase selectivity for the branched aldehyde derivative. Therefore, there is an urgent need for a catalyst exhibiting superior catalyst stability and activity while lowering a selection ratio of normal aldehyde to iso aldehyde (n/i ratio).